The present invention relates to absorbent articles which are primarily designed to receive and retain bodily discharges such asxe2x80x94and foremostxe2x80x94urine. Such articles are disposable hygiene articles like baby diapers, training pants, Adult Incontinence Articles and the like.
Absorbent Articles for receiving and retaining bodily discharges such as urine or faeces such as disposable diapers, training pants, adult incontinence articles are well known in the art, and significant effort has been spent against improving their performance. Such improvements generally aim at addressing the primary function of such articles, namely retaining body fluids, but also at minimising the negatives associated with wearing such articles by increasing the comfort of the wearer.
Such improvements can mostly be classified to primarily fall within either of two categories: primarily relating to xe2x80x9ccore technologyxe2x80x9d, i.e. xe2x80x9cabsorbencyxe2x80x9d in the broad sense of the word, or primarily relating to xe2x80x9cchassis technologyxe2x80x9d.
The first addresses how to pick up and retain the body waste (generally in some state of fluidity) in an xe2x80x9cabsorbent (or core) structurexe2x80x9d, whereby the waste material is acquired by the article (picked up) and then stored (retained), with potentially an additional step of distribution (in particular of urine) in between.
The second category dealsxe2x80x94generallyxe2x80x94with the so called xe2x80x9cchassis elementsxe2x80x9d, namely containing the body waste xe2x80x9cwithin the confinement of the articlexe2x80x9d
by separating the absorbent (core structure) and the outside, i.e. wearers garments, etc., by using an impermeable xe2x80x9cbacksheetxe2x80x9d;
or by preventing bodily exudates from escaping through the space between the absorbent article and the body of the wearer, such as by elasticised gatherings at leg and waist openings.
This also deals with enabling application of the article to the wearerxe2x80x94such as by providing closure means such as tapes, and maintaining the article on the wearer, such as through belt like arrangements often integrated into the application means.
With this terminology, xe2x80x9ccomfortxe2x80x9d for the wearer is at present predominantly being addressed by improving chassis elements, such as by adopting the chassis elements of the diaper to provide good xe2x80x9cfitxe2x80x9d of the article and to be soft and cushioning.
In PCT application WO 93/16669 (Alemany) or PCT application WO 93/21877 (Richardson) disposable diapers are described, whereby the comfort of the wearer is enhanced by introducing elasticised features such as allowing better body conformity even if the wearer is moving.
When considering the impact of cores on comfort, the general approach is to do so by using soft, non chafing materials for topsheets or minimising the thickness and/or volume of the dry article, preferably whilst maintaining softness of such cores. Recently, attempts have been made to also adopt the form and shape of the absorbent structure to allow good fit.
Since so called superabsorbent materials (or hydrogel forming materials) have found wide spread application in disposable absorbent articles, a number of marketed productsxe2x80x94such as PAMPERS as sold by The Procter and Gamble Co. or HUGGIES as sold by Kimberly-Clark Corp. in various countriesxe2x80x94underwent a remarkable reduction in the thickness of the products.
U.S Pat. No. 5.098.423 (Pieniak) describes disposable diapers, which attempts to address various xe2x80x9ccomfortxe2x80x9d aspects by providing xe2x80x9clow dry bulkxe2x80x9d structures, claiming that not only the dry thickness of the structure is relevant, but also other dimensions like
the cross-sectional area of the core in the crotch region;
the compressibility of the article in the crotch region and the resulting thickness of the article after folding;
size of the xe2x80x9cimpact zone of the articlexe2x80x9d;
distance of the (leg) elastic members of the article.
Hence, the core structures described herein can be called thin, but wide.
Further, an xe2x80x9cAbsorbency Efficiency Indexxe2x80x9d is described, by relating an amount of fluid, which should be picked up by the crotch region, to the volume of the dry core. The objective of this parameter is to allow designing towards high absorbency characteristics, capacity, in the crotch region. Thus is still a key objective to also absorb large amounts of urine in the crotch area, which, however, inevitably reduces comfort after loading significantly. This issue becomes even more pronounced with further improving the performance of absorbent articles yielding absorbent articles providing significantly better fluid handling performance, and hence an increase in overall wearing time and amount of fluid contained in such articles before being removed.
In U.S. Pat. No. 4,994,037 (Bernardin) absorbent articles are described, having a xe2x80x9creversed capacity profilexe2x80x9d. Therein, the ultimate storage capacity is positioned away from the crotch region. However, the disclosed designs for absorbent articles do not consider the fit requirement of fitting well between the legs of the wearer, nor the fluid handling requirements, such as achieving appropriate skin dryness and fluid acquisition. Whilst these designs arrange the capacity away from the loading point, they were not concerned with how to effectively achieve the fluid transport to these storage regions.
Hence it is an object of the present invention to provide absorbent articles having an improved fit also when being loaded, together with good fluid handling performance, especially by using materials having particularly suitable fluid distribution properties.
It is a further object of the present invention to achieve this by selectively placing ultimate storage capacity away from the crotch region.
It is a further object of the present invention to provide this feature without detrimentally affecting the fit when dry by providing designs with low bulk in the article crotch region.
It is a further object of the invention to achieve this by using Superabsorbent polymers.
It is a further object of the invention, to achieve this by using porous absorbent materials, such as made by HIPE polymerisation.